1. Field of the Invention
The present invention relates to a method for determining the wear resistance of a material surface of a sample, utilizing a counter-body and a belt, with the belt being run between the sample and a counter-body, while the belt is pressed against the sample with a previously determined force, thereby allowing for the wear resistance of the sample surface to be determined.
A related apparatus for determining the wear resistance of a material surface of a sample, comprising a counter-body and a belt is also taught, the apparatus being for holding and transport which holds and carries the belt over the sample surface. Further included is a counter-body holding device and a counter-body held by the counter-body holding device vertically movable, while the counter-body holding device is arranged so that the counter-body can be pressed on the side of the belt, which is turned away from the sample surface.
The determination of the wear resistance of very thin surface layers has quickly gained importance in industry, as considerable miniaturization efforts have progressed and innovative technologies, such as the micro-system technique, are greatly increasing. Micro tribological optimizations of rails, bearings and sliding contacts require, for example, the use of extremely thin layers, which thicknesses are very often on the sub-micro scale and which have to be tested and optimised optimized regarding their mechanical wear resistance. The prior art fails to disclose adequate methods and devices for accomplishing these tasks.
2. Description of the Prior Art
The known micro-scratch tester based on the AFM method is not suitable for the determination of practically usable and transferable results since the scratch results, which are gained with the aid of a thin needle, permit no determination regarding the actual areal wear in practice.
For a local resolution examination of wear characteristics on material surfaces, the ball wear method is used. Here, calotte shaped grindings are produced by a 3-body-contact on the surface, which is to be measured. Optically measured, the grindings allow conclusions about wear resistance. The grinding is produced by a ball turning on the material surface, which is moistened with a polishing slurry.
It is disadvantageous that the polishing medium can cause a change its grinding characteristics, for example, by being soiled with abraded material, by deposit of particles and by evaporation losses of the fluid. The polishing slurry can, furthermore, operate as a wear passive material when particles deposit in soft surfaces and it is unevenly spread over the counter-body's contact route. The surface of the ball is also altered. A frequently change of balls is necessary.
Furthermore, this prior art method of load variation is limited by a reduction of the calotte radius. Also, the pressure force of the ball can only be used restrictively. When evaluating the measurement, failures of the calotte form (especially rounding of the edges) can falsify the measurement results.
In summation, all of the prior art testing methods provide only limitedly transferable results for each application (scratch-test) or cannot be restricted to small lateral areas to be analyzed (sand trickle test).
Using the reflection method for testing lacquers, the results show great dispersion, while the Taber test does not allow an analysis of extremely thin surface areas.
A further testing device for determining the abrasive wear resistance of magnetic heads in video recorders is published in Bushan, B. et al. “Tribology and Mechanics” Sp. 22, ASLE Spec. Publ. Park Ridge 1987 from van Groenou et al. In this so-called “Sphere-on-Tape-Test,” a tape with an abrasive effect is run between a sample surface and a lateral fixed, weight loaded counter-body ball. The abrasive tape is pressed on the sample by the pressure of the counter-body ball, so that a wear calotte is formed on the sample surface. The sample is then taken out of the device at different points of time and the depth of the calotte is measured.
With this device, for example, deviations of the tape thickness or complicated topographies of the samples lead to damping difficulties. Furthermore, no exact sample positioning control is possible and, due to the removal and fixing of the sample in the device, an automation of the measurement is not feasible. Consequently, an in situ wear measurement is not possible.
From the conference contribution (international conference on wear of materials in 1983) of Broese van Groenou, among others, wear magnet recorders were examined. For these devices, a running through belt is pressed with its coating, which is equipped with magnet porter information, against a sample with the assistance of a counter-body. For determining the wear, the generated deepening in the sample body is measured after removing the belt and the wear is determined. In a disadvantageous way, a method of this kind does not allow an in situ measurement. As the wear is generated by the magnetic coating, the material of the belt itself remains without influence.
Finally, U.S. Pat. No. 6,247,356 B1 shows a device for testing the hardness of materials.